Enhanced reliability of service in mobile networks

ABSTRACT

The technology described in this application increases the reliability of mobile networks. A radio communications node broadcasts a primary radio network code that indicates that subscribed mobile user equipment terminals may obtain service from a primary PLMN operator. In certain circumstances, the node may receive an instruction to broadcast a standby radio network code during a standby mode of operation. During the standby mode of operation, second mobile user equipment terminals that are not subscribed may obtain radio communications service from the primary PLMN operator.

TECHNICAL FIELD

The technical field relates to radio and/or wireless communications, andmore particularly, to improving the reliability of radio and/or wirelesscommunications service.

BACKGROUND

The ubiquitous nature of mobile networks makes their reliability crucialas society grows increasingly dependent on the mobile service providedto billions of users. While the service provided by mobile networks maybe used for private communication purposes, other purposes such as,business, health, education, and the like may also rely on the constantconnectivity offered by mobile networks. Accordingly, it may be ajarring experience for businesses and individuals if they loseconnectivity to a mobile service.

In a typical cellular radio system (e.g., a mobile network), wirelessterminals (also known as mobile stations and/or user equipment units(UEs)) communicate via a radio access network (RAN) to one or more corenetworks. The RAN covers a geographical area which is divided into cellareas, with each cell area being served by a base station, e.g., a radiobase station (RBS), which in some networks may also be called, forexample, a “NodeB” (UMTS) or “eNodeB” (LTE). A cell is a geographicalarea where radio coverage is provided by the radio base stationequipment at a base station site. Each cell is identified by an identitywithin the local radio area, which is broadcast in the cell. The basestations communicate over the air on radio frequencies with the UEswithin range of the base stations.

In some versions of a radio access network, several base stations aretypically connected (e.g., by landlines or microwave) to a controllernode (such as a radio network controller (RNC) or a base stationcontroller (BSC)) which supervises and coordinates various activities ofthe plural base stations connected thereto. The radio networkcontrollers are typically connected to one or more core networks.

Typically mobile networks are designed with some degree of redundancy.For example, the loss of one base station might not affect the overallservice provided by a network. However, more pervasive failures causedby human error, natural disasters (e.g., a tsunami), or man-madedisasters (e.g., a military conflict) may happen. In such instances theloss of network resources may impact the service provided to UEs. Theloss of network resources and mobile service may be more pronounced inan emergency situation (e.g., a natural disaster) where such mobileservice may play a vital role for emergency personnel.

In certain instances, there may be multiple mobile networks in aparticular geographic location. A first mobile network may fail in thelocation, but other mobile networks may still be operational at the samelocation. Yet, subscribed UEs of the affected mobile network may not beable to obtain service from the other mobile networks to which they donot subscribe.

As an example, in 2005, hurricane “Gudrun” in southern Sweden broughtdown multiple base stations. The inoperability of certain base stationscaused service disruptions for some users. However, while base stationsfor certain mobile operations were inoperable in certain areas, in manyareas, at least one mobile network operator had an operable basestation. Accordingly, even though there may have been an operable basestation (with an associated mobile network operator) within range of anotherwise “stranded” mobile subscriber, the subscriber may not have beenable get service from that mobile network operator.

One reason “stranded” mobile subscribers may not obtain service fromother mobile network operators is a lack of national roaming agreementsbetween mobile operators. National roaming agreements may allow users toroam between different operators in the same country. However, inpractice certain mobile operators may be reluctant to make such nationalroaming agreements due to business reasons. For example, mobile networkoperators may choose to compete on the quality of coverage they providein a given country.

Where there are no national roaming agreements, one possible workaroundmight be to use a SIM card from another country. An international roamercould select any of the local networks whenever at least one isavailable. However, the option of using an international SIM card maynot be available for every mobile subscriber. Moreover, such a solutionmay not work for local inhabitants affected by a hurricane who may needimmediate communications service.

Accordingly, some level of cooperation among mobile network operatorsmay be needed. Indeed there may be reasons for mobile operators tocooperate in such emergency situations. First, government entities mayprovide incentives for cooperation. Second, outages in coverage mayaffect the economic viability of a company that runs a mobile network.Third, cooperation among operators may decrease the overall cost ofproviding high reliability mobile service for subscribers. Mobilenetwork operators may realize that multiple networks on essentially thesame national coverage area can provide inherent reliability for networkfailures. Conversely, achieving the same level of reliability within asingle mobile network may require an extreme degree of redundancy with acorrespondingly high price tag. Accordingly, the aggregate reliabilityof national mobile operators may provide an economic justification forthe operators to cooperate.

Cooperation between national mobile operators may take various forms.One approach may be an emergency-only national roaming agreement, (e.g.,one that is only invoked when there is some substantial networkfailure). However, such an approach may be possible only if thenecessary business and legal agreements have been made ahead of time.Further, there may be additional problems with such a solution.

First, the UEs may be configured in such a way that the other networksare marked as forbidden such that the UE may not select other networksindependent of any prior standard roaming agreements. Second,reprogramming UEs (e.g., by redefining a forbidden public land mobilenetwork (PLMN) list, or using a steering of roaming feature to directthe terminal to (or away from) a specific PLMN) on the fly during anemergency situation may not be viable because: 1) a mass reconfigurationof all connected UEs may further congest the mobile network; and 2) theUEs not connected (and thus in need of connectivity the most) may notreceive the reconfiguration instructions.

It will be appreciated that emergency calling (e.g., 911) may ignoreeven forbidden networks. However, emergency calling may be only a verylimited service. Disconnected users may want to have all thecommunication services provided by their normal service (e.g., to callfamilies, access the internet, get the latest news, etc). Furthermore,usage of emergency call services may present a new problem if people ina disaster area can only access emergency numbers. This may lead topeople calling the emergency number for non-emergency situations (e.g.,to get information, etc). Accordingly, this may increase the call burdento emergency call centers during a situation such as hurricane Gudrun.

Thus, it will be appreciated that the current methods are notsufficient. Accordingly, it would be desirable to provide a methodand/or system of increasing mobile network reliability.

SUMMARY

The technology described in this application provides techniques toimprove mobile communications service reliability. A radiocommunications node in a first radio communications network is operatedby a primary public land mobile network (PLMN) operator that providesradio communications service to first mobile user equipment terminalssubscribed to the primary PLMN operator during a first normal mode ofoperation. The radio communications node includes radio circuitry thatbroadcasts a primary radio network code associated with the primary PLMNoperator. The primary radio network code indicates that first mobileuser equipment terminals may obtain service from the primary PLMNoperator. The radio communications node also includes a receiverconfigured to receive an instruction to broadcast a standby radionetwork code. A second different PLMN operator provides radiocommunications service during the first normal mode of operation tosecond mobile user equipment terminals subscribed to the second PLMNoperator. The second mobile user equipment terminals are substantiallynot allowed to obtain service from the primary PLMN operator during thefirst normal mode of operation. The receiver, in response to thereceived instruction, enters a standby mode of operation and causes theradio circuitry to broadcast both the primary radio network code and thestandby radio network code to permit one or more of the second mobileuser equipment terminals to obtain radio communications service from theprimary PLMN operator during the standby mode of operation.

A feature of a non-limiting example embodiment is that thecommunications service for the primary PLMN operator includes usingfirst radio resources allocated to the primary radio network operatorand the communications service from the second PLMN operator includesusing second radio resources that are at least partially different fromthe first radio resources.

Another feature of a non-limiting example embodiment is where the secondPLMN operator operates a second radio communications network, and thestandby mode of operation corresponds to an emergency situation whereone or more radio communications nodes in the first radio communicationsnetwork and/or in the second radio communications network are no longeravailable.

A further feature of a non-limiting example embodiment is that thestandby radio network code is associated with a standby PLMN identifier.

A feature of a non-limiting example embodiment is mobility managementcircuitry that coordinates mobility during the standby mode of operationto facilitate handover of ongoing mobile user equipment terminalcommunications between at least one communication node of the primaryPLMN operator and at least one communication node of the second PLMNoperator.

Another feature of a non-limiting example embodiment is the second PLMNoperator operating a second radio communications network, and whereinthe first and second radio communications networks are logical networks.

A further feature of a non-limiting example embodiment is the secondPLMN operator operating a second radio communications network that is adifferent type of radio access technologies.

A feature of a non-limiting example embodiment is that the standby radionetwork code is an emergency indicator flag that instructs second mobileuser equipment terminals to override a standard radio communicationsnetwork selection process.

In another non-limiting example embodiment, a controller node interactswith a first radio communications network operated by a primary PLMNoperator to communicate with at least one radio communications node ofthe first radio communications network. The one radio communicationsnode broadcasts a primary radio network code associated with the primaryPLMN operator during a normal operational mode. The controller nodeincludes a communications interface that sends an instruction to the oneradio communication node to enter a standby mode and to broadcast astandby radio network code. The primary PLMN operator provides radiocommunications service during the normal operational mode to firstmobile user equipment terminals that are primary PLMN operatorsubscribers. A second PLMN operator provides radio communicationsservice during the normal operational mode to second mobile userequipment terminals that are second PLMN operator subscribers. Thesecond mobile user equipment terminals are excluded from substantiallyobtaining the radio communications service of the primary PLMN operatorduring the normal operational mode but are allowed to access the radiocommunications service of the primary PLMN operator during the standbymode.

A feature of a non-limiting example embodiment is a communicationsnetwork fault determiner that automatically sends instructions to atleast one radio communication node when a fault is detected in the firstradio communications network.

Another feature of a non-limiting example embodiment is wherecommunications interface is adapted to send an instruction tosubstantially all radio base station nodes within the firstcommunications network to enter the standby mode.

A further feature of a non-limiting example embodiment is an externalinterface that sends a request to the second PLMN operator to activate asecond standby mode to broadcast a second standby code and the firstmobile user equipment terminals are allowed to access a second radiocommunications service of the second PLMN operator during the secondstandby mode.

A feature of a non-limiting example embodiment is that the controllernode is located in an O&M node, a core network node, or a radio networkcontrol node

In a further non-limiting example embodiment, a method of increasingreliability of access to a radio communications network for mobile userequipment terminals is provided. A first primary radio network codeassociated with a first PLMN operator that provides radio communicationsservice to first mobile user equipment terminals subscribed to the firstPLMN operator is established. The first PLMN operator operates a firstradio communications network. A standby radio network code associatedwith the first PLMN operator and related to a second PLMN operator isestablished. The second PLMN operator operates a second radiocommunications network and provides radio communications service to aset of second mobile user equipment terminals subscribed to the secondradio communications provider. The first primary radio network code isbroadcast. A standby mode is activated. The standby radio network codeis broadcast in response to the standby mode being activated. Service tothe first PLMN operator for the second mobile user equipment terminalsis substantially denied when the standby mode is inactive. Service fromthe first PLMN operator is provided for the second mobile user equipmentterminals when the standby mode is active.

A feature of a non-limiting example embodiment is automaticallycontrolling the activation of the standby mode.

Another feature of a non-limiting example embodiment is activating thestandby mode automatically when a predetermined percentage of networknodes in the first radio communications network become inoperative.

A further feature of a non-limiting example embodiment is, in responseto activating the standby mode, the first PLMN operator sends a requestto the second PLMN operator to broadcast a second standby code and thesecond standby code facilitates first mobile user equipment terminalsobtaining service from the second PLMN operator.

A feature of a non-limiting example embodiment when activating thestandby mode is done in response to a request from the second PLMNoperator to activate the standby mode

Another feature of a non-limiting example embodiment is when the firstcommunications network includes a first core network component and afirst radio access network component, and the standby radio network codeis associated with a standby core network component that is at leastpartially separate from the first core network component

A further feature of a non-limiting example embodiment is where thestandby core network is logically separate from the first radiocommunications network, but is substantially physically the same as thefirst radio communications network.

Additional features and/or advantages may be realized in certainnon-limiting example embodiments. For example, during bigger networkfailures, users may continue to obtain communications service if atleast one of the networks continues to function, thereby increasing thereliability of service.

National roaming may be restricted to emergency situations. Accordingly,regular business practices may be maintained in normal circumstances(e.g., when a standby PLMN is not active).

As users may be able to access a communication service, emergency callcenters may be relieved from calls that are not emergency-related.Accordingly, emergency call centers may become more efficient when theyare needed most (e.g., during emergencies).

An operator that provides a standby PLMN feature may be able to chargeother operators for the services it provides for inbound roamers. Thischarge may be settled in a roaming agreement, and may be higher thannormal roaming charges. Accordingly, an operator with a reliable networkmay obtain extra revenue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a non-limiting example diagram of two networkoperators with overlapping coverage areas;

FIG. 1B illustrates another non-limiting diagram of two networkoperators servicing their respective subscribers;

FIG. 2A illustrates a non-limiting diagram of two network operatorsservicing their respective subscribers after some base stations arerendered inoperable;

FIG. 2B illustrates another non-limiting diagram of two networkoperators after some base stations are rendered inoperable, with somesubscribers obtaining service from an alternative network operator;

FIG. 3A illustrates a non-limiting example diagram of a controller nodemanaging a PLMN list;

FIG. 3B illustrates a non-limiting example diagram of a communicationsnode broadcasting a PLMN list;

FIG. 4 is a diagram of a non-limiting example communications network;

FIG. 5 is a block diagram of a non-limiting example controller node;

FIG. 6 is a block diagram of a non-limiting example base station;

FIG. 7A is a signaling diagram illustrating one set of non-limitingexample procedures between operators;

FIG. 7B is another signaling diagram illustrating a set of non-limitingexample procedures between operators; and

FIGS. 8A, 8B, 8C, and 8D are diagrams of non-limiting example standbyPLMN embodiments.

DETAILED DESCRIPTION

In the following description, for purposes of explanation andnon-limitation, specific details are set forth, such as particularnodes, functional entities, techniques, protocols, standards, etc. inorder to provide an understanding of the described technology. It willbe apparent to one skilled in the art that other embodiments may bepracticed apart from the specific details disclosed below. In otherinstances, detailed descriptions of well-known methods, devices,techniques, etc. are omitted so as not to obscure the description withunnecessary detail. Individual function blocks are shown in the figures.Those skilled in the art will appreciate that the functions of thoseblocks may be implemented using individual hardware circuits, usingsoftware programs and data in conjunction with a suitably programmedmicroprocessor or general purpose computer, using applications specificintegrated circuitry (ASIC), and/or using one or more digital signalprocessors (DSPs). The software program instructions and data may bestored on computer-readable storage medium and when the instructions areexecuted by a computer or other suitable processor control, the computeror processor performs the functions.

Thus, for example, it will be appreciated by those skilled in the artthat block diagrams herein can represent conceptual views ofillustrative circuitry or other functional units embodying theprinciples of the technology. Similarly, it will be appreciated that anyflow charts, state transition diagrams, pseudocode, and the likerepresent various processes which may be substantially represented in anon-transitory computer readable medium and so executed by a computer orprocessor, whether or not such computer or processor is explicitlyshown.

The functions of the various elements including functional blocks,including but not limited to those labeled or described as “computer”,“processor” or “controller” may be provided through the use of hardwaresuch as circuit hardware and/or hardware capable of executing softwarein the form of coded instructions stored on computer readable medium.Thus, such functions and illustrated functional blocks are to beunderstood as being either hardware-implemented and/orcomputer-implemented, and thus machine-implemented.

In terms of hardware implementation, the functional blocks may includeor encompass, without limitation, digital signal processor (DSP)hardware, reduced instruction set processor, hardware (e.g., digital oranalog) circuitry including but not limited to application specificintegrated circuit(s) (ASIC), and (where appropriate) state machinescapable of performing such functions.

In terms of computer implementation, a computer is generally understoodto comprise one or more processors, or one or more controllers, and theterms computer and processor and controller may be employedinterchangeably herein. When provided by a computer, processor, orcontroller, the functions may be provided by a single dedicatedcomputer, processor, or controller, by a single shared computer,processor, or controller, or by a plurality of individual computers,processors, or controllers, some of which may be shared or distributed.Moreover, use of the term “processor” or “controller” shall also beconstrued to refer to other hardware capable of performing suchfunctions and/or executing software, such as the example hardwarerecited above.

The technology may be used in any type of cellular radio communications.For ease of description, the term user equipment (UE) encompasses anykind of radio communications terminal/device, mobile station (MS), PDAs,cell phones, laptops, etc.

Referring now more particularly to the drawings in which like referencenumerals indicate like parts throughout the several views. FIG. 1Aillustrates a non-limiting example diagram of two network operators withoverlapping mobile network coverage areas. As shown, Public Land MobileNetwork (PLMN) A 102 and PLMN B 104 have coverage areas thatgeographically overlap.

FIG. 1B illustrates another non-limiting diagram of two networkoperators servicing their respective subscribers. Base stations 102A,102B, 102C, and 102D (e.g., NodeBs) facilitate mobile radiocommunications for PLMN A 102. UEs 106A, 106B, 106C, 106D, and 106E maybe user equipment devices that are subscribed and obtain service fromPLMN A 102. The individual UEs may obtain service through a base stationthat facilitates mobile communications service with a given geographicalarea. Accordingly, UE 106A obtains service (e.g., over allocated radioresources through techniques such as TDM or FDM) through base station102A; UE 106B obtains service through base station 102C; UE 106C obtainsservice through base station 102D; UE 106D obtains service through basestation 102D; and UE 106E obtains service through base station 102B.

Similarly, UEs 108A, 108B, 108C, 108D, and 108E are subscribed to andobtain service from PLMN B 104. Accordingly, UE 108A obtains servicethrough base station 104A; UE 108B obtains service through base station104A; UE 108C obtains service through base station 104B; UE 108D obtainsservice through base station 104C; and UE 108E obtains service throughbase station 104D.

FIG. 2A illustrates a non-limiting diagram of the two network operatorsshown in FIG. 1B servicing their respective subscribers after some basestations are rendered inoperable (e.g., because of a disaster). As shownin FIG. 2A, base stations 104A, 102B, 102D, and 104D of FIG. 1B areinoperable and now referred to as downed base stations 204A, 202B, 202D,and 204D. As these base stations of PLMN A and PLMN B's network are nowdown, some of their respective UE subscribers may not be able to receiveservice. Specifically, UEs 108A and 108B no longer able to obtainservice as downed base station 204A is inoperable. Furthermore, UEs 108Aand 108B may not be in range of any other operable base stations thatare operated by PLMN B (e.g., 104C). Similarly, downed base station 202Bis unable to provide service to UE 106E. As there are no operable basestations with range of UE 106E that are operated by PLMN A, UE 106E isnot able to obtain mobile service from PLMN A. Likewise, the disablingof base station 202D may cut service from UEs 106C and 106D. Similar tothe previous UEs, there may be no base stations operated by PLMN Awithin range that are able to provide service to these UEs.

Downed base station 204D may not be able to provide service to UE 108E.However, unlike the previous UEs, UE 108E is within range of anotherbase station operated by PLMN B. Accordingly, UE 108E may obtain servicefrom another active base station 104C and thus avoid a serviceinterruption.

FIG. 2B illustrates another non-limiting diagram of two networkoperators after some base stations are rendered inoperable, with somesubscribers obtaining service from an alternative non-subscribed networkoperator according to a non-limiting example embodiment. As with FIG.2A, UEs 108A, 108B, 106E, 106C, and 106D are not able to obtain mobileservice from their respective PLMN operators because of downed basestations 204A, 202B, 202D, and 204D. The lack of an operable basestation within range of the UEs may “cut” them off from mobile servicealtogether. However, while there may not be any operable base stationsoperated by their respective PLMN operators within range, there may bebase stations operated by other non-subscribed PLMN operators withinrange.

As discussed above, absent a predefined roaming agreement betweendifferent PLMN operators, UEs subscribed to one PLMN operator may markother PLMN operators to which the UEs are not subscribed as “forbidden.”In a non-limiting example embodiment, base stations operated by PLMNoperators may broadcast a network code (e.g., a PLMN ID where a PLMN IDmay be a Mobile Country Code (MCC) plus a Mobile Network Code (MNC)).The broadcast network code identifies the PLMN operator that the basestation is associated with (however, as discussed below, a base stationmay be associated with more than one PLMN operator, code, etc). Thus,each of the base stations broadcasts a network code. UEs then perform anetwork code (e.g., PLMN id) selection procedure to decide which of thebase stations that the UE will obtain service from that is operated byits subscribed PLMN operator. It will be appreciated that the describedselection process may be automatic, manual, pre-programmed, etc. In somenon-limiting example embodiments, the selection process may be apre-programmed process where only approved operators (e.g., a subscribedoperator or an operator with a roaming agreement), and their associatedbase stations, are candidates for selection by a UE during the UEselection process.

FIG. 2B shows UEs 108A, 108B, 106E, 106C, and 106D are now connected tobase stations not operated by their respective subscribed PLMN operator.As discussed above, individual base stations may broadcast network codes(e.g., a PLMN id) that identify which subscribed UEs operators mayobtain service from each base station. For example, during a normal modeof operation base station 102A broadcasts a PLMN code that is directlyassociated with PLMN operator A. Thus, a UE (e.g., UE 106A) that may besubscribed to operator A may recognize the broadcast network code andattempt to obtain service from base station 102A. Other UEs (e.g., UEs108A or 108B) that are not subscribers or not otherwise able to obtainservice from PLMN operator A may also receive the broadcast networkcode. However, unlike a subscribed UE, these non-subscribed UEs may havethe broadcast network code marked as forbidden. Accordingly,non-subscribed UE's are not able to obtain service from base stationswhere the broadcast network code is marked as forbidden.

In a non-limiting example embodiment, a base station may selectivelybroadcast both its regular (e.g., primary) PLMN code and a standby PLMNcode during a standby mode. In the example above, base station 102Abroadcasts a network code directly associated with PLMN Operator Ainforming PLMN Operator A UE subscribers (e.g., UE 106A) that mobileservice is available from base station 102A. However, in FIG. 2B basestation 102A also broadcasts a second standby network code (e.g., astandby PLMN id). The standby network code (discussed in more detailbelow) may be selectively broadcast by a base station (e.g., basestation 102A may begin broadcasting the standby network code in responseto the failure of base station 204A).

The second standby network code may alert other non-subscribed UEs thatthey may obtain service from base station 102A through PLMN Operator A.Furthermore, in certain example embodiments, the second standby networkcode may not be marked as forbidden by the non-subscribed UEs.Accordingly, non-subscribed UEs may add the second standby network codeto their selection procedure for obtaining mobile communicationsservice. For example, the second standby network code broadcast by basestation 102A may be received by UEs 108A and 108B. As UEs 108A and 108Bmay be within range of base station 102A, the UEs may add the secondstandby network code (and its associated base station and PLMN Operator)to their selection process. As base station 102A is the only operationalbase station within range, UEs 108A and 108B obtain service from basestation 102A. As can be seen in FIG. 2B, unsubscribed UEs 108A and 108Bestablish a radio connection via base station 102A to obtain servicethrough Operator A. Similarly, base station 104C and base station 104Bbroadcasts standby network codes. Accordingly, UEs 106E, 106D, and 106Cmay attempt to obtain service from the base stations now broadcastingstandby network codes.

It will be appreciated that in certain non-limiting example embodiments,an operator whose base stations transmit a standby network code mayimpose certain restrictions on the use of the PLMN associated with thestandby network code. These special policy rules may apply limits totraffic so that congestion may be avoided. Further, different thresholdsmay apply to UEs obtaining service through a standby network code versusUEs obtaining service through a regular or normal network code.Furthermore, operators may define special classes of subscribers anddifferentiate them (e.g., governmental agencies may get a higher trafficquota).

Certain non-limiting example embodiments of a communications network mayinclude a controller node. For example, such a controller node mayprovide operations and maintenance (O&M) for a mobile communicationsnetwork. In some non-limiting example embodiments, a controller node mayinclude a core network node, a radio control node, or the like.

In certain example embodiments, the controller node may control when astandby network code (e.g., PLMN code) may be broadcast by basestations. FIG. 3A illustrates a non-limiting example diagramillustrating procedures performed by a controller node managing a PLMNcode list. In step 302, the controller node determines the standbystatus of the network so as to determine whether the standby PLMN codeshould be activated.

One non-limiting technique for accomplishing this determination processis to have an automated process determine when the standby code may beactivated. For example, a controller node interfaces with other nodeswithin a communications network and monitors the overall health andoperational status of the network. The controller node may be able todetermine, for example, a percentage of communication nodes (e.g., basestations or NodeBs) that are operational on the network (or areoperational on a particular geographic portion of the communicationsnetwork). If the percentage of operational nodes drops below a certainamount the controller node may, in step 302, determine “yes” that thestandby status should be switched on and proceed to the step 304.However, if the automatic determination program decides “no”, thecontroller node loops around the “no” path to check the status again.

Alternatively, or in addition to, the determination of a standby statusmay be an input from a terminal (e.g., a keyboard) or other userinterface. Thus, operational personnel may manually determine whether ornot to activate the standby status.

Once a controller node determines that a standby mode may be activated,then in step 304 the controller node transmits configurationinstructions, information, etc., to the rest of the communicationsnetwork. Such instructions instruct various nodes within the networkthat the standby mode is to be activated. For example, when the basestations in the communications network receive instructions to enter thestandby mode, the PLMN code list broadcast by the base stations isupdated to include a standby PLMN code.

Furthermore, the core network may be updated to include the standby PLMNas an approved PLMN for which the core network provides service. Next,in step 308, the updated PLMN list (e.g., the list updated in the RAN)may then be broadcast by the base stations in the communicationsnetwork. The updated PLMN list now includes the primary PLMN codeassociated with the PLMN operator and the additional and newly-addedstandby PLMN code related to another PLMN operator. It will beappreciated that there may be various techniques for facilitating theupdating and broadcasting of the standby PLMN. Such techniques mayinclude, for example, locally storing alternate PLMN lists and switchingbetween those lists upon request, receiving a PLMN code and dynamicallyadding the id to the broadcast PLMN list, storing a PLMN id locally andreceiving an instruction to add the id to the list, etc.

FIG. 3B illustrates a non-limiting example function block diagram of acommunications node (e.g., a base station) broadcasting a PLMN list. Instep 320, a communication node broadcasts a primary PLMN code. This PLMNcode may alert subscribed UEs that they may obtain service from the PLMNoperator associated with the primary PLMN code. Thus, in step 322, firstmobile UEs (subscribers of the PLMN operator) allowed to access thecommunications network operated by the PLMN operator that isbroadcasting the primary PLMN code.

Next in step 324 the communication node receives instructions tobroadcast a second PLMN code. As discussed above, such an instructionmay be provided by a controller node. In any case, once the instructionis received, in step 326, a second standby PLMN code is broadcast by thecommunications node. The broadcasting of the second PLMN code in standbymode permits a second group of unsubscribed mobile UEs to access thecommunications network operated by the PLMN operator.

It will be appreciated that the second group of unsubscribed mobile UEsare not permitted to access the communications network prior to thebroadcasting of the second PLMN code (e.g., during a normal operationalmode). Accordingly, the broadcasting of the second PLMN code mayfacilitate access to the communications network for a second group ofmobile UEs that are not subscribers of the PLMN operator.

FIG. 4 is a diagram of a non-limiting example communications network400. The communications network 400 has subscriber UEs 418, 420, 422,and 424 and is operated by a PLMN operator (e.g., Operator A in FIG. 1)In this example, the communications network 400 includes a core network402 and a RAN (e.g., a UTRAN) that includes RNCs 404 and 406 and NodeBs410, 412, 414, and 416.

Core network 402 provides various core functionalities forcommunications network 400. It will be appreciated that core network 402may composed of numerous separate core networks that may interface witheach other. Further that such core networks may be logically and/orphysically separate core networks. Such services may include, forexample: 1) an authentication capability to determine whether a UErequesting a service from the communication network 400 is authorized todo so; 2) a call routing or switching functionality that directs and/ordetermines how calls are routed/switched within the communicationsnetwork and/or other networks; and 3) links to other core networksoperated by other PLMN operators. The communications network 400includes an Operations and Maintenance (O&M) node 408 that configures,allocates, monitors, etc; the nodes in the communications network 400.The O&M node 408 may gather various statistics, such as, for example,the number of calls being handled, the number of subscribers attached tothe network, the type of services being used, or the like. The O&M node408 may then act on (e.g., through alarms, triggers, messages, etc.) thecollected data and perform configuration requests on the core network402 and/or other nodes (e.g, RNCs 404 and 406 and NodeBs 410, 412, 414,and 416) within the communications network.

The Radio Network Control (RNC) Nodes 404 and 406 communicate with thecore network 402 and control NodeBs 410, 412, 414, 416. The NodeBs inturn communicate with UEs 418, 420, 422, and 424 over a radio interface.

Each NodeB also broadcasts a network code that identifies the primaryPLMN network for that NodeB. As shown in FIG. 4, NodeBs 410 and 412broadcast a network code “A” that is directly associated with a PLMNoperator A. UEs 418 and 420 are subscribers of operator A. Accordingly,the broadcast of the network code “A” lets UEs 418 and 420 know thatNodeBs 410 and 412 are part of a communications network that they arepermitted to access because the UEs are subscribers of Operator A.

NodeBs 414 and 416 broadcast two network codes, a primary “A” code andstandby “B” code, in a standby mode of operation. Accordingly, listeningUEs that do not have codes “A” and “B” marked as forbidden may attemptto access communications network 400 through the above NodeBs.Specifically, UEs 422 and 424 have network code “A” labeled as aforbidden network (e.g., one that they know they are not able toaccess—because they are not subscribers). However, the UEs 422 and 424also do not have network code “B” marked as forbidden and may seek toobtain service from communications network 400 through NodeBs 414 and416.

It will be appreciated that configuration of the NodeBs for the networkcodes to be broadcast may be controlled by the O&M node or other similarnode. Further, in other non-limiting example embodiments all NodeBs maybe configured to broadcast a standby code instead of just a portion theNodeBs in a communications network.

FIG. 5 is a block diagram of a non-limiting example controller nodeaccording to an example embodiment. PLMN configuration controller 500includes a standby PLMN activation controller 502. Alternately, thefunction of the standby PLMN activation controller 502 may be performedby CPU 504. PLMN activation controller 502 determines when a standbyPLMN may be activated. The PLMN activation controller 502 interfaceswith a central processing unit (CPU) 504. CPU 504 may then interfacewith an operator interface 508. Operator interface 508 may include, forexample, a keyboard, a mouse, a touch screen, or other such device thatallows an operator to perform input commands. Operator interface 508 mayfacilitate manual decision making of when a standby PLMN may beactivated.

CPU 504 also interfaces with a communications interface 506 thatfacilitates the communication of commands, instructions, andconfiguration data to nodes within a communications network (e.g., suchas base station 600 in FIG. 6). Accordingly, when the PLMN configurationcontroller 500 decides to control the PLMN status of a communicationsnetwork it communicates such commands to the rest of the communicationsnetwork.

FIG. 6 is a block diagram of a non-limiting example base stationaccording to an example embodiment. Base station 600 communicates withUEs. 418, 420, 422, and 424 in FIG. 4 over a radio interface using radiocircuitry 608. The radio circuitry 608 interfaces with CPU 602. CPU 602accepts incoming data from radio circuitry 608 (e.g., call data) andpasses it on to a network communications interface 604. Alternatively,or in addition to, CPU 602 may communicate information from thecommunications interface 604 to CPU 602 that may then be passed on to betransmitted by radio circuitry 608. CPU 602 also interfaces with amemory that stores a broadcast PLMN list 606. The broadcast PLMN list606 includes a list of one or more PLMN codes to be broadcast by basestation 600. The CPU 602 accesses the broadcast PLMN list 606 andinstructs radio circuitry 608 to broadcast the list of PLMN codescontained in the broadcast PLMN list 606.

The broadcast PLMN list may be stored in a memory medium such as, forexample, volatile (e.g., RAM) or non-volatile memory (e.g., diskmemory). The communications interface 604 may receive instructions from,for example, PLMN configuration controller 500, to update the broadcastPLMN list 606 with a new PLMN code (e.g., a standby PLMN code).Accordingly, CPU 602 may receive the instruction and then causes a writeoperation to take place that updates the broadcast PLMN list with thenew PLMN code. Thus, a standby PLMN may be added to the broadcast PLMNlist 606.

The switching on and off of the standby PLMN may involve the O&M systemof a communications network reconfiguring the RAN nodes to start or stopadvertising the standby PLMN. While such a reconfiguration may be donemanually, it may be preferable if the O&M system automatically switchesthe standby PLMN on/off. The trigger to switch the standby PLMN on maybe based on some indication of a major failure in one of the networks ora disaster that may lead to a major failure. The trigger may be manual,but may also be based on an automatic indication from the O&M systemdetecting a fault in the RAN, in the core network, and/or in thetransport network.

The switching on or off of the standby PLMNs may be harmonized in thedifferent networks (e.g., networks that have standby agreements inplace). This may be accomplished by an offline method or automaticallyvia a redundant communication scheme using feedback from the O&Msystems. Further, an external organization, such as a governmentalagency, may be used to decide when a “communication emergency situation”has arisen (e.g., when standby PLMNs may be activated).

FIG. 7A is a signaling diagram illustrating one set of non-limitingexample procedures between operators according an example embodiment.Operator A and Operator B may setup a procedure that activates thestandby PLMNs in each of the networks operated by Operators A and B.Operator A and Operator B may set up O & M emergency triggers. Asdiscussed above, such triggers may be manual (e.g., operator input) orautomatic (e.g., based on a percentage of downed network capacity). Oncethe O & M emergency trigger is set off, two things may occur. First, asdiscussed above, the communications network may be configured to switchon a standby PLMN in the radio access network (e.g., the RAN and NodeBsof the network) and switch on the standby PLMN in the CN (e.g., corenetwork). Second, the trigger may cause a request to be sent to theother operator (e.g., Operator B) to activate the standby PLMN in theother operator's network. Accordingly, the “trigger” for the othernetwork may be the request from the initially triggered network. Thus,the networks of Operators A and B may be automatically harmonized basedon one trigger.

Alternatively, the networks of Operators A and B may be setup to bemanually harmonized. In other words, a trigger may activate the standbyPLMN in Operators B's network. Then, Operator A may manually activatethe O & M trigger (e.g., through personnel of Operator A manuallysetting off the trigger) to activate the standby PLMN in Operator A'snetwork.

FIG. 7B is another signaling diagram illustrating a set of non-limitingexample procedures between operators according an example embodiment.Initially, there are standard communications between UE and Network A(e.g., the network operated by Operator A). Standard communicationsbetween the UE and network A is between a particular base station ofnetwork A and the UE. Network A and network B are both broadcasting onlyprimary PLMN codes.

At some later point base stations in network A may be renderedinoperable (e.g., due to a hurricane, etc). As a result of the downedbase stations, the UE may loose connectivity to network A. In responseto the downed base stations, an emergency trigger or request may beactivated (e.g., as shown in FIG. 7A). Thus, network A sends a requestto network B asking network A to activate and broadcast a standby PLMN.In response, network B activates the standby PLMN and sends anacknowledgement to network A that the standby PLMN has been activated.

It will be appreciated that the acknowledgement signal need not be sentand network A may assume that the request has been carried out. Further,in response to the acknowledgement, network A may activate its standbyPLMN code.

Once the standby PLMN code has been activated, the standby PLMN isbroadcast by network B. Upon receiving the newly broadcast PLMN code,the UE recognizes that the standby PLMN code is not on a list offorbidden list of networks. Alternatively, or in addition, the broadcastPLMN code may be recognized as being on a list of approved PLMN networksthat it may obtain service from. Accordingly, the UE may request access(e.g., request to obtain service from) to the network broadcasting thestandby PLMN code.

It will be appreciated that the UE may consider the standby PLMN code tobe a “separate” network from the primary broadcast PLMN code of networkB. However, the network associated with the standby PLMN code may be thesame physical communications network as the communications networkassociated with the primary PLMN code. Thus, the “two” networksassociated with the two different PLMN codes may be logically separatebut physically the same. It will be appreciated that in othernon-limiting embodiments, a separate physical network may be providedfor a separate PLMN code.

In any event, once the UE requests access to network B, anauthentication process may need to be carried out. Accordingly, networkB may request subscriber information from network A (e.g., to verifythat the UE is a subscriber of the operator of network A). In responseto the request for information, network A may lookup the information andreturn the resulting subscriber information to network B. Network B thencommunicates the UE that access to Network B's resources have beengranted. The UE now establishes a connection and operates throughnetwork B's resources even though the resources of network A have beenrendered inoperable for the UE.

This implementation of a standby PLMN allows UEs to roam into a standbyPLMN when their own network fails. This may be facilitated by nationalroaming agreements between standby PLMNs and other “regular” PLMNs. Asstandby PLMNs may be switched on in emergency, or the like, this mayallow the setup of national roaming agreements to help achievereliability in situations like an emergency situation. Further suchagreements may not disrupt regular business and competition betweenoperators in normal situations.

FIGS. 8A, 8B, 8C, and 8D are diagrams of non-limiting example standbyPLMN implementations according to example embodiments.

FIG. 8A shows a non-limiting example standby PLMN (e.g., SPLMN)implementation. In this embodiment all the PLMNs (e.g., operators)define a standby PLMN as a new logical operator corresponding to thesame physical PLMN. In defining a new logical operator the standby PLMNmay use the same nodes as used by the “regular” PLMN. In alternativenon-limiting embodiments, the SPLMN may use different physical nodes inaddition to being separate logically. Furthermore, in this embodimentall operators (e.g., A, B, and C) have separate RANs and core networks.

Accordingly, the created standby PLMN may make a national roamingagreement with the other operators (e.g., as shown by the solid linesbetween SPLMNs and normal PLMNs). In another non-limiting exampleembodiment a “broker entity” may be setup to reduce the effort forsetting up roaming agreement so that a “full mesh” (e.g., O(n²)) ofroaming agreements may be avoided.

Taking for example the agreement between SPLMN A and PLMN B. UEs of PLMNB may not be allowed to access the network resources of PLMN A. However,when SPLMN A is activated the roaming agreement (represented by thesolid line) may allow UEs of PLMN B to obtain service through SPLMN A.

FIG. 8B shows another non-limiting example standby PLMN (e.g., SPLMN)implementation. It may be possible that roaming agreements are madebetween a set of operators while other operators are left out. In thiscase, operators may be left out and may not be able to make any roamingagreements with the standby operators. This may be because agreementsmay be done on a bilateral (or multilateral) basis. Accordingly,operators A and B may make a standby roaming arrangement and leaveoperator C alone. However, even with a limited set of operators, standbyroaming agreements may still be desirable.

FIG. 8C shows a further non-limiting example standby PLMN (e.g., SPLMN)implementation. Here, operators may decide to run a separate corenetwork for a Standby PLMN. This may add further core network redundancyto a system. Such an implementation may help centralize the handling ofan emergency situation and share the costs thereof Further, such animplementation may require that the RANs of the individual operators areset up for network sharing between the regular PLMN and the StandbyPLMN.

FIG. 8D shows another non-limiting example standby PLMN (e.g., SPLMN)implementation. When multiple operators share the same RAN (andassociated base stations), then it may be possible for those operatorsto decide to run a single standby PLMN. A single standby PLMN may beimplemented by one of the PLMNs as a new logical network. It will beappreciated that a separate physical standby PLMN may be implemented aswell. One benefit to such an implementation may be to reduce the costsassociated with a standby PLMN. Most failures may happen in the RAN of acommunications network. Further, a core network may use internalredundancies to improve fault tolerance. Accordingly, a standby PLMN forshared RAN resources may be a reasonable option.

The use of national roaming in relation to the standby PLMNs may allowextended coverage for UEs whose own network fails at their currentlocation. However, UEs may suffer performance problems when movingbetween a regular PLMN network and a standby PLMN network.

This may be because a UE in connected mode which moves from a goodcoverage area to a place with no coverage (e.g., because a base stationin that area is not available) may lose connectivity before the UE mayselect a new network with proper coverage. This process typically takessome amount of time and may cause disruption to the end user.

Accordingly, to improve mobility performance, the RAN nodes may beconfigured to enable handover to the RAN of other operators in anemergency situation (e.g., from a regular PLMN operator to a standbyPLMN operator). To accomplish this, RAN nodes may order UEs to also makemeasurements on the neighboring networks (based on pre-configuredfrequency bands that are sent to the terminal during the setup ofmeasurements), and trigger a handover to the RAN of the other operator(e.g., the standby PLMN operator) based on the radio measurements. Thismay require that the RAN nodes be configured in a special “emergencymode” to also consider the other SPLMNs as potential targets forhandover.

For idle mode mobility as well as for connected mode mobility, it is maybe desirable for the operators to provide connectivity between therespective core network nodes (MMEs, SGSNs, GGSNs, SGWs and PGWs) sothat the context of the registered user is transferred during aLocation/Routing/Tracking area update.

The above configuration to enable mobility from one network to anothermay require some work to fully set up and maintain. Further, such asetup may also require a degree of trust between operators (e.g., theymay need to exchange security keys between core network entities).However, a similar type of configuration may take place near the networkborder even in normal circumstances, as more and more users may desire aseamless handover from one network to a neighboring network as they walkor drive through a national border (e.g., between the U.S. and Canada,or between member states of the European Union). Further, operators mayre-use experiences from these types of network configuration settings.

Certain non-limiting example embodiments may be applied to LTE and 3Gnetworks. Certain non-limiting example embodiments may be applied toboth circuit-switched and packet-switched services. Certain non-limitingexample embodiments may use network sharing in 3G and may be applied toboth supporting UEs and non-supporting UEs.

As discussed above, certain non-limiting example embodiments may use anetwork configuration where the same physical node may belong to twological networks: the normal PLMN and the standby PLMN. Such aconfiguration may apply to signaling nodes such as a Serving GPRSSupport Node (SGSN) or a Mobility Management Entity (MME), or to userplane nodes such as a Gateway GPRS Support Node (GGSN) or a Public DataNetwork (PDN) Gateway (GW). This is facilitated by configuring a nodewith a logical Standby PLMN in addition to the primary PLMN. If astandby PLMN is used, a Home Subscriber Server (HSS) node may stillcorrespond to the home PLMN as the user is in a roaming situation. Thesubscription may be configured so that it allows for a roaming scenario,with the logical standby PLMN providing GW functionality (e.g., VisitedAddress Allowed flag should be turned on).

The principles described above may apply to different types ofcommunication networks. Non-3GPP networks such as wireless local areanetworks (WLAN) may provide further capacity and coverage for 3GPPmobile networks for UEs that support the given non-3GPP accesstechnology. Non-3GPP networks may access and be connected to a 3GPPnetwork. This may allow, for example, a single non-3GPP access point toprovide access for multiple PLMNs. In certain example non-limitingembodiments the deployment of non-3GPP access points (e.g., WLANs) mayprovide redundancy for a PLMN operator. Such implementations may allowfor access to the same network in multiple ways. Accordingly, if oneaccess technique fails, a back-up option may be used to access the samenetwork.

In certain example non-limiting embodiments, operators may have theirown non-3GPP access deployments. Accordingly, it may be possible toshare the non-3GPP access during an emergency situation in a similar wayas for 3GPP accesses. During an emergency situation (e.g., when astandby PLMN is turned on), the non-3GPP access may also connect toother operators. This may require a reconfiguration of the non-3GPPaccess points to facilitate connection to the new operators. Such animplementation may not require a new PLMN code, as the non-3GPP accesscan provide a list of accessible operators to the UE.

One example technique of carrying out such an implementation may be touse WLANs that are capable of advertising more than one SSID (ServiceSet ID). As such, the broadcast SSIDs may be used to advertise availableoperators via a WLAN. Such an implementation may improve thediscoverability of available networks. It will be appreciated that theuse of a new SSID may not be required as multiple operators may bereached through one SSID.

In certain non-limiting example embodiments, an “emergency indicatorflag” may be used in a system broadcast channel. Such an indicator couldbe the same as is used for the Earthquake and Tsunami Warning System, orit could be a different indicator. When UEs detect the broadcast anemergency indicator flag, they may override the regular PLMN selectioncriteria, and select a PLMN that is on the Forbidden PLMN list.Alternatively, or in addition, operators may define a PLMN selectionlist that applies to such emergencies. Such an emergency PLMN selectionlist could by configured by an Access Network Selection and DiscoveryFunction (ANDSF) or other protocols. Accordingly, national roaming inemergency situations may be enabled for non-supporting networks (e.g.,2G networks).

In a non-limiting example embodiment an emergency roaming agreement mayneed to be setup before activation. A new UE function may be needed tolisten to the new broadcast flag. Such an implementation may overridethe normal PLMN selection rules under emergency. It will be appreciatedthat such an implementation may not be practical for legacy UEs (e.g.,as they would not be able to handle the new UE function).

In another non-limiting example embodiment, a UE could provide an“emergency button” for the user with the purpose of overriding normalnetwork selection rules and try networks that are normally forbidden.

In a further non-limiting example embodiment, as an alternative toadding the standby PLMN to the list of supported PLMNs in the RAN, theprimary PLMN advertised by RAN may be replaced with the Standby PLMN.

In summary, the technology described herein increases the reliability ofmobile network access through the use of standby PLMNs and the like insituations like those described in the background.

Although various embodiments have been shown and described in detail,the claims are not limited to any particular embodiment or example. Noneof the above description should be read as implying that any particularelement, step, range, or function is essential such that it must beincluded in the claims scope. The scope of patented subject matter isdefined only by the claims. The extent of legal protection is defined bythe words recited in the allowed claims and their equivalents. Allstructural and functional equivalents to the elements of theabove-described preferred embodiment that are known to those of ordinaryskill in the art are expressly incorporated herein by reference and areintended to be encompassed by the present claims. Moreover, it is notnecessary for a device or method to address each and every problemsought to be solved by the technology described, for it to beencompassed by the present claims. No claim is intended to invoke 35U.S.C. §112, 6^(th) paragraph unless the words “means for” or “step for”are used. Furthermore, no embodiment, feature, component, or step inthis specification is intended to be dedicated to the public regardlessof whether the embodiment, feature, component, or step is recited in theclaims.

1. A radio communications node in a first radio communications networkoperated by a primary public land mobile network (PLMN) operator toprovide radio communications service to first mobile user equipmentterminals subscribed to the primary PLMN operator during a first normalmode of operation, the node comprising: radio circuitry configured tobroadcast a primary radio network code associated with the primary PLMNoperator which indicates that first mobile user equipment terminals mayobtain service from the primary PLMN operator; and a receiver configuredto receive an instruction to broadcast a standby radio network code,wherein a second different PLMN operator provides radio communicationsservice during the first normal mode of operation to second mobile userequipment terminals subscribed to the second PLMN operator, whereinsecond mobile user equipment terminals are substantially not allowed toobtain service from the primary PLMN operator during the first normalmode of operation, wherein the receiver is configured, in response tothe received instruction, to enter a standby mode of operation and tocause the radio circuitry to broadcast both the primary radio networkcode and the standby radio network code to permit one or more of thesecond mobile user equipment terminals to obtain radio communicationsservice from the primary PLMN operator during the standby mode ofoperation.
 2. The radio communications node of claim 1, whereincommunications service from the primary PLMN operator includes usingfirst radio resources allocated to the primary radio network operatorand communications service from the second PLMN operator includes usingsecond radio resources that are at least partially different from firstradio resources.
 3. The radio communications node of claim 1, whereinthe second PLMN operator operates a second radio communications network,and wherein the standby mode of operation corresponds to an emergencysituation where one or more radio communications nodes in the firstradio communications network and/or in the second radio communicationsnetwork are no longer available.
 4. The radio communications node ofclaim 1, wherein the standby radio network code is associated with astandby PLMN identifier.
 5. The radio communications node of claim 1,further comprising mobility management circuitry configured tocoordinate mobility during the standby mode of operation to facilitatehandover of ongoing mobile user equipment terminal communicationsbetween at least one communication node of the primary PLMN operator andat least one communication node of the second PLMN operator.
 6. Theradio communications node of claim 1, wherein the second PLMN operatoroperates a second radio communications network, and wherein the firstand second radio communications networks are logical networks.
 7. Theradio communications node of claim 1, wherein the second PLMN operatoroperates a second radio communications network, and wherein the firstand second communications networks are different types and use differentradio access technologies.
 8. The radio communications node of claim 1,wherein the standby radio network code is an emergency indicator flagthat instructs second mobile user equipment terminals to override astandard radio communications network selection process.
 9. The radiocommunications node of claim 1, wherein the standby code is used by theprimary PLMN operator and related to the second PLMN operator through astandby roaming agreement.
 10. A controller node configured to interactwith a first radio communications network operated by a primary PLMNoperator, the controller node operable to communicate with at least oneradio communications node of the first radio communications network, theat least one radio communications node configured to broadcast a primaryradio network code associated with the primary PLMN operator during anormal operational mode, the controller node comprising: acommunications interface adapted to send an instruction to the at leastone radio communication node to enter a standby mode and to broadcast astandby radio network code, wherein the primary PLMN operator providesradio communications service during the normal operational mode to firstmobile user equipment terminals that are primary PLMN operatorsubscribers, wherein a second PLMN operator provides radiocommunications service during the normal operational mode to secondmobile user equipment terminals that are second PLMN operatorsubscribers, and wherein the second mobile user equipment terminals areexcluded from substantially obtaining the radio communications serviceof the primary PLMN operator during the normal operational mode but areallowed to access the radio communications service of the primary PLMNoperator during the standby mode.
 11. The controller node of claim 10,further comprising a communications network fault determiner, thecommunications network fault determiner configured to automatically sendthe instruction to the at least one radio communication node when afault is detected in the first radio communications network.
 12. Thecontroller node of claim 10, wherein the communications interface isfurther adapted to send an instruction to substantially all radio basestation nodes within the first communications network to enter thestandby mode.
 13. The controller node of claim 9, wherein the controllernode is located in one of an O&M node, a core network node, or a radionetwork control node.
 14. The controller node of claim 10, furthercomprising an external interface configured to send a request to thesecond PLMN operator to activate a second standby mode to broadcast asecond standby code, wherein the first mobile user equipment terminalsare allowed to access a second radio communications service of thesecond PLMN operator during the second standby mode.
 15. A method ofincreasing reliability of access to a radio communications network formobile user equipment terminals, the method comprising: establishing afirst primary radio network code associated with a first PLMN operatorthat provides radio communications service to first mobile userequipment terminals that are subscribed to the first PLMN operator, thefirst PLMN operator operating a first radio communications network;establishing a standby radio network code that is associated with thefirst PLMN operator and related to a second PLMN operator, the secondPLMN operator providing radio communications service to second mobileuser equipment terminals that are subscribed to the second radiocommunications operator, the second PLMN operator operating a secondradio communications network; broadcasting the first primary radionetwork code; activating a standby mode; broadcasting the standby radionetwork code in response activating the standby mode; substantiallydenying service to the first PLMN operator for the second mobile userequipment terminals when the standby mode is inactive; and providingservice from the first PLMN operator for the second mobile userequipment terminals when the standby mode is active.
 16. The method ofclaim 15, wherein activating the standby mode is controlledautomatically.
 17. The method of claim 16, wherein activating thestandby mode is automatically determined when a predetermined percentageof network nodes in the first radio communications network becomeinoperative.
 18. The method of claim 15, wherein, in response toactivating the standby mode, the first PLMN operator sends a request tothe second PLMN operator to broadcast a second standby code, the secondstandby code to facilitate first mobile user equipment terminals toobtain service from the second PLMN operator.
 19. The method of claim15, wherein activating the standby mode is done in response to a requestfrom the second PLMN operator to activate the standby mode.
 20. Themethod of claim 15, wherein the first communications network includes afirst core network component and a first radio access network component,and wherein the standby radio network code is associated with a standbycore network component that is at least partially separate from thefirst core network component.
 21. The method of claim 20, wherein thestandby core network is logically separate from the first radiocommunications network, but is substantially physically the same as thefirst radio communications network.